Valve mechanism for rock drills



April 18, 1939. I TERRY 2,154,788

VALVE MECHANISM FOR ROCK DRILLS Filed June 22, 1937 H I s ATTORNEY.

Patented Apr. 18, 1939 UNITED STATES Ahii QFFliZE VALVE. MECHANISM FOR ROCK DRILLS Application June 22, 1937, Serial No. 149,555

3 Claims.

This invention relates to rock drills, and more particularly to a valve mechanism for effecting the distribution of pressure fluid to the percussive element of rock drills of the hammer type.

One object of the invention is to obtain a light weight valve mechanism of simplified construction capable of effecting a rapid distribution of pressure fluid and a consequent rapid action of the percussive element of the rock drill.

Other objects will be in part obvious and in part pointed out hereinafter.

In the drawing accompanying this specification and in which similar reference numerals refer to similar parts,

Figures 1 and 2 are longitudinal views of a valve mechanism constructed in accordance with the practice of the invention and showing the valve in its limiting positions.

Referring more particularly to the drawing, 20 20 designates the valve mechanism .and 2i a portion of a rock drill cylinder to which the valve mechanism is applied.

The cylinder 2| is recessed to provide the usual piston chamber 22 which is closed at its front 25 and rear ends by plates 23 and 24, respectively. Within the piston chamber 22 is a reciprocatory hammer piston 25 having a stem 26 at its front end slidable through the plate 23 to strike against a working implement (not shown).

The valve mechanism is shown arranged on the side of the cylinder 2|. It comprises a valve chest 21 having a bore of uniform diameter throughout and extending from one end to the other of the valve chest to form a valve cham- 35 ber 28. The ends of the valve chamber 28 are sealed by plugs 29 having apertures 30 to receive a bolt 3| which extends axially through the valve chamber and has a nut 32 threaded thereon to act against one of the plugs 29 for clamp- 40 ing them securely to the valve chest 21.

In the side of the valve chest is a threaded aperture 33 which may be connected with a source of pressure fluid supply through a suitable conduit (not shown), and communicating 45 with the aperture 33 is a supply passage 34 which extends toward the extremities of the valve chamber wherewith it communicates through branch passages 35. Pressure fluid issuing from the passages 35 flows directly into the ends of the 50 valve chamber 28, and in the wall of the cylinder 2| are inlet passages 36 and 3'! to afford communication between the front and rear ends, respectively, of the valve chamber and the corresponding ends of the piston chamber 22.

The pressure fluid admitted into the front end of the piston chamber for actuating the piston rearwardly is exhausted from the piston chamber by an exhaust passage 38 opening into the intermediate portion of the valve chamber, whence it passes to the atmosphere through an 5 exhaust port 39 in the valve chest. Similarly, the pressure fluid employed for actuating the piston 25 forwardly on its working stroke flows from the piston chamber through an exhaust passage 45 which also opens into the intermedimy ate portion of the valve chamber and is communicable with the exhaust port 39.

Within the valve chamber 23 is a distributing valve El of the reciprocatory spool type to control communication between the branch passages and the inlet passages 35 and 3: and also to control communication between the exhaust passages 38-40 and the exhaust port 39. The valve comprises an intermediate stem 42 having a bore 43 which is in slidable and sealing 0 tom surfaces constitute actuating surfaces 49 .9.

and 50, respectively, subjected intermittently to pressure fluid for actuating the valve from one limiting position to the other. The pressure fluid employed for this purpose is conveyed to the actuating surfaces by crossed kicker passages 5i 3. and located entirely Within the valve.

The kicker passage 5: is in constant communication with the exhaust passage 49 and extends from they periphery of the head 45 through the'stem 43 and opens into the pressure chamber ll for supplying pressure fluid to the actuating surface 49. In like manner, the kicker passage 52 is in constant communication with the exhaust passage 38 and extends from the periphery of the head 44 through the valve stem 42 and 45 opens into the pressure chamber 48 for supplying pressure fluid to the actuating surface 50.

Suitable closures are provided for the pressure chambers 41 and 48 in the form of extensions 53 carried by the plugs 29 and extending 50 into the pressure chambers and in the peripheries of the extensions 53 are annular grooves 54 through which pressure fluid flows from the branch passages 35 to the inlet passages.

On the free or outer ends of the portions of 55 the heads 44 and 45 encircling extensions 53 are annular holding surfaces. and 56 against which pressure fluid flowing through the grooves 5 3 acts to hold the valve in its limiting positions.

The operation of the device is as follows: Assuming the Valve to be in position to admit pressure fluid into the rear end of the piston chamber 22 for driving the piston 25 forwardly on its working stroke pressure fluid flowsfrom the passage 34 through the rearmost annular groove 54 and the inlet passage 31 into the rearward end of the piston chamber and actuates the piston 25 forwardly. During the charging of the rear end of the piston chamber the pressure fluid acts: against the holding surface 56 and holds the valve in its foremost limiting position in which the head 24 overlies the front branch passage 35.

As the piston 25 proceeds. forwardly it uncovers the exhaust passage 49. Pressure fluid then flows through the kicker passage 5| into the pressure chamber i! and acts against the actuating surface 59 to shift the valve 4! rear- Wardly, thereby moving the head 45 into position to overlie the rear passage and cut off communication between the supply passage 34 and the inlet passage 31.

In the new position of the valve the annular groove 46 will establish communication between the exhaust passage 56 and the exhaust port 39 and the pressure fluid in the rearward end of the piston chamber is then exhausted to the atmosphere through these passages and, inasmuch as the kicker passage 5| is in constant communication with the exhaust passage 40, the pressure fluid acting against the actuating surface 49 Will also be exhausted to the atmosphere.

After the valve has been shifted rearwardly pressure fluid flows through the front annular groove 54 and the inlet passage 35 and returns the piston to its initial position. During its rearward movement the piston uncovers the exhaust passage 33, whereupon pressure fluid flows from said exhaust passage through the kicker passage 52 into the pressure chamber 18 and, acting against the actuating surface 50, shifts the valve 4| again forwardly. In this position of the valve the exhaust passage 38 is communicated with the exhaust port 39, by the annular groove 46, and the pressure fluid utilized for moving the piston 25 rearwardly and that acting against the actuating surface 55 will then be exhausted to the atmosphere.

I claim:

1. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a piston therein, an exhaust passage for the piston chamber, a valve chest having a valve chamber, inlet passages leading from the valve chamber to the piston chamber, a valve in the valve chamber to control communication between pressure fluid supply and the inlet passages and hav' ing opposed holding surfaces subjected to pressure fluid flowing to the inlet passages for holding the valve in the limiting positions, means on the valve for controlling the exhaust passage, means on the valve chest and the valve to define pressure chambers at the ends of the valve chamber, actuating surfaces on the valve each c0nstituting an end. surface for a pressure chamber, and. kicker passages within the valve to convey pressure fluid from the piston chamber to the actuating surface for moving the valve.

2. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a piston therein, a valve chest having a valve chamber and an exhaust port, inlet passages leading from the valve chamber to the piston chamber, exhaust passages for the piston chamber opening into the valve chamber, a valve in the valve chamber to control communication between pressure fluid supply and the inlet passages and to control communication between the exhaust passages and the exhaust port, means on the valve chest and the valve to define pressure chambers at the ends of the valve chamber, opposed actuating surfaces within the valve each constituting an end surface for a pressure chamber, kicker passages within the valve to convey pressure fluid from the exhaust passages to the actuating surfaces for throwing the valve and affording constant communication between the pressure chambers and the exhaust passages, and opposed holding surfaces on the valve subjected to pressure fluid flowing to the inlet passages to hold the valve in the limiting positions.

3. In a fluid actuated rock drill, the combination of a casing having a piston chamber and a piston therein, a valve chest, a bore of uniform diameter in the valve chest forming a valve chamber, an exhaust port for the valve chamber, inlet passages leading from the ends of the valve chamber to the corresponding ends of the piston chamber, exhaust passages for the piston chamber opening into the valve chamber, a valvein the valve chamber slidable on the surface of the bore and having a peripheral groove to afford communication between the exhaust passages and the exhaust port, heads on the ends of the valve to control communication between pressure fluid supply and the inlet flanges, actuating surfaces in the heads, crossed kicker passages within the valve to convey pressure fluid from the exhaust passages to the actuating surfaces for actuating the valve, and holding surfaces on the ends of the heads subjected to pressure fluid flowing to the inlet passages for holding the valve in the limiting positions.

EDWARD F. TERRY. 

